Meet the site
The Trio is a puzzle of a wreck: a big ferro-cement barge about 50 m long, name unknown, which local lore says was being towed from Pittwater to Sydney Harbour when it foundered with a cargo that included a concrete yacht. It was found on 15 July 1988 by Bob Mansfield and two companions and named for the three of them. Sydney Dive Charters record it as a hopper barge lost at an unknown date. It lies upright about 2 km off Mona Vale Beach on sand that shelves from 52 to 54 m, with the deck about 5 m off the bottom at roughly 46 m, making it the northernmost of the deep wrecks between Long Reef and Broken Bay and one of the least visited. The layout is simple. A large winch and a row of bollards mark the bow. Three holds open along the deck: the first once held a deteriorating ferro-cement yacht, now mostly gone, and the other two are empty. At the stern is a steering compartment, memorable chiefly for containing a toilet, and a below-deck compartment forward of it. The midship hull has started to break down, and a hole into the aft hold gives access to the small power-plant space. Because the whole structure is concrete over steel mesh rather than plate, it has held its shape better than the steel barges at Long Reef but offers little marine growth. Fish life is moderate, with bullseyes and jewfish in the holds. The Trio's interest is novelty and depth: it is a worthwhile change for teams who dive the Long Reef group regularly, worth a dive every now and again rather than a destination in itself. It suits experienced decompression divers on trimix with a competent boat handler, and anchoring is awkward unless the hook is placed directly on the deck.
Research this site before booking Stored site notes may be historical. These questions highlight gaps without turning old instructions into a current dive plan.
The Trio wreck is recorded as Wreck in Sydney Northern Beaches. The listed access is boat. Confirm the actual meeting point, route and permission to visit; a map pin does not establish any of these.
Topics flagged by the stored research
These are questions prompted by the existing notes, not a verified or complete hazard assessment.
- Current and timing
- Ask how the operator assesses the current window for the actual route. Historical tide notes are not a departure instruction.
- Other water users
- Ask about vessel activity, exclusion areas and the agreed surface arrangements.
- Water movement
- Ask how swell and local exposure affect the proposed entry, exit and route.
Historical access notes exist for this record, but have not been independently verified for current use. Request current directions from the operator or site manager rather than following an old entry description.
Questions, answered
Is The Trio wreck suitable for my certification?
The record lists Technical (decompression). That does not establish suitability for every route or day. Share your training, recent experience and equipment needs with the operator and ask about the specific proposed dive.
Can I book The Trio wreck through YouDive?
YouDive is an independent research directory. Contact an operator directly to confirm whether it currently runs the trip, the inclusions and the booking terms.
What you might see
Bullseyes, jewfish, nannygai, kingfish, occasional wobbegong, sparse encrusting growth
Location
Large ferro-cement barge of unknown name lost under tow between Pittwater and Sydney, lying upright about 2 km off Mona Vale Beach in 51–54 m with its deck at about 46 m.
Before you make plans
Conditions, access and operator schedules can change. This is a location guide, not a dive plan. Ask a local operator about current conditions and suitability for your training and experience.
Sources & further reading
michaelmcfadyenscuba.infosydneydivecharters.com.auRecord updated 26 Sept 2026. Source claims are being reviewed.